Medium: water; 900 mL.

Apparatus 2: 50 rpm.

Time: 45 minutes.

Procedure— Determine the amount of C8H11NO3·HCl dissolved employing the procedure set forth in the Assay for niacin or niacinamide, pyridoxine hydrochloride, riboflavin, and thiamine, Method 1 under Water-Soluble Vitamins Tablets by using filtered portions of the solution under test suitably diluted with Dissolution Medium, if necessary, in comparison with a Standard solution having a known concentration of USP Pyridoxine Hydrochloride RS in the same medium.

Tolerances— Not less than 75% (Q) of the labeled amount of C8H11NO3·HCl is dissolved in 45 minutes.

Procedure for content uniformity— Transfer 1 Tablet, previously finely powdered, to a 500-mL volumetric flask containing about 300 mL of water, shake for about 30 minutes, and dilute with water to volume. Filter a portion of the mixture, discarding the first 25 mL of the filtrate. Dilute a suitable aliquot of the subsequent filtrate quantitatively and stepwise with dilute hydrochloric acid (1 in 100) so that the concentration of pyridoxine hydrochloride is about 10 µg per mL. Dissolve an accurately weighed quantity of USP Pyridoxine Hydrochloride RS in dilute hydrochloric acid (1 in 100), and dilute quantitatively and stepwise with the same solvent to obtain a Standard solution having a known concentration of about 10 µg per mL. Concomitantly determine the absorbances of both solutions in 1-cm cells at the wavelength of maximum absorbance at about 290 nm, with a suitable spectrophotometer, using dilute hydrochloric acid (1 in 100) as the blank. Calculate the quantity, in mg, of C8H11NO3·HCl in the Tablet taken by the formula: in which T is the labeled quantity, in mg, of pyridoxine hydrochloride in the Tablet, D is the dilution factor, C is the concentration, in µg per mL, of USP Pyridoxine Hydrochloride RS in the Standard solution, and AU and AS are the absorbances of the solution from the Tablet and the Standard solution, respectively.

C(AU AU¢) / (AS AS¢)